400 CALIFORNIA ACADEMY OF SCIENCES. 



wiow. Caudal with two series of spots between each two rays. 



Eye nearly of the interorbital; first dorsal ray longer than the 



head; caudal obliquely subtruncate; pectoral spine with long, 



curved spines; head 3. (Giinther). brevicauda 365. 



cr. Occipital bordered by a single nuchal plate. 



x. A single series of large round spots between two dorsal rays, 

 similar spots on the caudal; scutes of the belly reduced to a 

 minimum; snout more regularly convex in transverse profile 

 than in wuchereri. Lat. 1. 26. robinii 366. 



xx. Two series of spots between two dorsal rays, the spots much 

 smaller than the eye; upper caudal lobe little shorter than the 

 lower; space between and behind ventrals naked, or with few 

 granules. Lat. 1. 26. wuchereri 367. 



xxx. Spots on the caudal much smaller than those on the dorsal, 

 which are large and ill-defined; caudal very obliquely truncate, 

 the lower lobe being much the longer; space beeween and be- 

 hind the ventrals mostly granular. Lat. 1. 25. johnii 368. 



344, Plecostomus emarginatus. 



Hypostomus emarginatus Cuvier & Valenciennes, xv, 500, 1840 



(Brazil). 

 Hypostomus emarginatus Kner, Hypostomiden, 260, 1853 (Barra do 



Kio Negro), not Cuv. & Val. 

 Plecostomus emarginatus Giinther, v, 233, 1864 (copied); Eigenm. 



& Eigenm. Proc. Cal. Acad. 2d Ser. i, 167, 1888 (Cudajas; San- 



tarem; Manacapuru; Tonantins; Obidos; Fonteboa; Tabatinga; 



Hyavary; Sao Paolo; Goyaz). 

 Hypostomus horridus Kner, Hypostomiden, 259, pi. i, fig. 1, 1853 



(Rio Guapore). 

 Plecostomus horridus Giinther, Cat. Fish. Brit. Mus. v, 232, 1864 



(copied); Peters, MB. Ak. Berl. 1877, 471 (Calabozo). 

 Hypostomus squalinum Schomburgk, Fish. Brit. Guiana, 142, pi. 2, 



1841 (Rio Branco, Rio Negro and Rio Essequibo). 

 Plecostomus scopularius Cope, Proc. Acad. Nat. Sci. Philad. 1871, 



55 and 286, pi. 16, figs. 1 and 2 (Ambyiacu). 

 Plecostomus tenuicauda Steindachner, Fisch-fauna Magd. Stromes, 



24, pi. vii, 1878 (Magdalen River); id. Fisch-fauna des Cauca and 



Fliisse bei Guayaquil, 11, 1879 (Cauca). 

 Habitat: Amazons and tributaries from Para to Ambyiaca; Guiana 



region; Rio Magdalena. 



H. emarginatus C. & V. was based on a dried speci- 

 men .51 m. long. The age and condition of the individ- 

 ual most likely prevented the discovery of the small 

 plates on the side of the occipital process, which therefore 



